Table Of ContentLIGO-P1000097-v12
PreprinttypesetusingLATEXstyleemulateapjv.5/2/11
IMPLICATIONS FOR THE ORIGIN OF GRB 051103 FROM LIGO OBSERVATIONS
J. Abadie1, B. P. Abbott1, T. D. Abbott60, R. Abbott1, M. Abernathy2, C. Adams3, R. Adhikari1, C. Affeldt4,11,
P. Ajith1, B. Allen4,5,11, G. S. Allen6, E. Amador Ceron5, D. Amariutei8, R. S. Amin9, S. B. Anderson1,
W. G. Anderson5, K. Arai1, M. A. Arain8, M. C. Araya1, S. M. Aston10, D. Atkinson7, P. Aufmuth4,11,
C. Aulbert4,11, B. E. Aylott10, S. Babak12, P. Baker13, S. Ballmer1, D. Barker7, S. Barnum15, B. Barr2,
P. Barriga16, L. Barsotti15, M. A. Barton7, I. Bartos17, R. Bassiri2, M. Bastarrika2, J. Bauchrowitz4,11,
B. Behnke12, A. S. Bell2, I. Belopolski17, M. Benacquista18, A. Bertolini4,11, J. Betzwieser1, N. Beveridge2,
P. T. Beyersdorf19, I. A. Bilenko20, G. Billingsley1, J. Birch3, R. Biswas5, E. Black1, J. K. Blackburn1,
L. Blackburn15, D. Blair16, B. Bland7, O. Bock4,11, T. P. Bodiya15, C. Bogan4,11, R. Bondarescu21, R. Bork1,
M. Born4,11, S. Bose22, M. Boyle23, P. R. Brady5, V. B. Braginsky20, J. E. Brau24, J. Breyer4,11, D. O. Bridges3,
2 M. Brinkmann4,11, M. Britzger4,11, A. F. Brooks1, D. A. Brown25, A. Brummitt26, A. Buonanno27,
1 J. Burguet-Castell5, O. Burmeister4,11, R. L. Byer6, L. Cadonati28, J. B. Camp30, P. Campsie2, J. Cannizzo30,
0 K. Cannon1,a, J. Cao31, C. Capano25, S. Caride32, S. Caudill9, M. Cavaglia29, C. Cepeda1, T. Chalermsongsak1,
2 E. Chalkley10, P. Charlton33, S. Chelkowski10, Y. Chen23, N. Christensen14, S. S. Y. Chua34, S. Chung16,
C. T. Y. Chung35, F. Clara7, D. Clark6, J. Clark36, J. H. Clayton5, R. Conte37, D. Cook7, T. R. C. Corbitt15,
n N. Cornish13, C. A. Costa9, M. Coughlin14, D. M. Coward16, D. C. Coyne1, J. D. E. Creighton5,
a T. D. Creighton18, A. M. Cruise10, A. Cumming2, L. Cunningham2, R. M. Culter10, K. Dahl4,11, S. L. Danilishin20,
J
R. Dannenberg1, K. Danzmann4,11, K. Das8, B. Daudert1, H. Daveloza18, G. Davies36, E. J. Daw38, T. Dayanga22,
5 D. DeBra6, J. Degallaix4,11, T. Dent36, V. Dergachev1, R. DeRosa9, R. DeSalvo1, S. Dhurandhar39, I. Di
2 Palma4,11, M. D´ıaz18, F. Donovan15, K. L. Dooley8, S. Dorsher41, E. S. D. Douglas7, R. W. P. Drever42,
J. C. Driggers1, J. -C. Dumas16, S. Dwyer15, T. Eberle4,11, M. Edgar2, M. Edwards36, A. Effler9, P. Ehrens1,
] R. Engel1, T. Etzel1, M. Evans15, T. Evans3, M. Factourovich17, S. Fairhurst36, Y. Fan16, B. F. Farr43,
E D. Fazi43, H. Fehrmann4,11, D. Feldbaum8, L. S. Finn21, M. Flanigan7, S. Foley15, E. Forsi3, N. Fotopoulos5,
H M. Frede4,11, M. Frei44, Z. Frei45, A. Freise10, R. Frey24, T. T. Fricke9, D. Friedrich4,11, P. Fritschel15,
V. V. Frolov3, P. Fulda10, M. Fyffe3, J. Garcia7, J. A. Garofoli25, I. Gholami12, S. Ghosh22, J. A. Giaime9,3,
.
h S. Giampanis4,11, K. D. Giardina3, C. Gill2, E. Goetz32, L. M. Goggin5, G. Gonza´lez9, M. L. Gorodetsky20,
p S. Goßler4,11, C. Graef4,11, A. Grant2, S. Gras16, C. Gray7, R. J. S. Greenhalgh26, A. M. Gretarsson46,
- R. Grosso18, H. Grote4,11, S. Grunewald12, C. Guido3, R. Gupta39, E. K. Gustafson1, R. Gustafson32,
o B. Hage4,11, J. M. Hallam10, D. Hammer5, G. Hammond2, J. Hanks7, C. Hanna1, J. Hanson3, J. Harms1,
r G. M. Harry15, I. W. Harry36, E. D. Harstad24, M. T. Hartman8, K. Haughian2, K. Hayama47, J. Heefner1,
t
s M. A. Hendry2, I. S. Heng2, A. W. Heptonstall1, V. Herrera6, M. Hewitson4,11, S. Hild2, D. Hoak28,
a K. A. Hodge1, K. Holt 3, T. Hong23, S. Hooper16, D. J. Hosken48, J. Hough2, E. J. Howell16, B. Hughey15,
[ S. Husa49, S. H. Huttner2, D. R. Ingram7, R. Inta34, T. Isogai14, A. Ivanov1, W. W. Johnson9, D. I. Jones50,
G. Jones36, R. Jones2, L. Ju16, P. Kalmus1, V. Kalogera43, S. Kandhasamy41, J. B. Kanner27, E. Katsavounidis15,
2
W. Katzman3, K. Kawabe7, S. Kawamura47, F. Kawazoe4,11, W. Kells1, M. Kelner43, D. G. Keppel4,11,
v
A. Khalaidovski4,11, F. Y. Khalili20, E. A. Khazanov51, N. Kim6, H. Kim4,11, P. J. King1, D. L. Kinzel3,
3
J. S. Kissel9, S. Klimenko8, V. Kondrashov1, R. Kopparapu21, S. Koranda5, W. Z. Korth1, D. Kozak1,
1 V. Kringel4,11, S. Krishnamurthy43, B. Krishnan12, G. Kuehn4,11, R. Kumar2, P. Kwee4,11, M. Landry7,
4 B. Lantz6, N. Lastzka4,11, A. Lazzarini1, P. Leaci12, J. Leong4,11, I. Leonor24, J. Li18, P. E. Lindquist1,
4 N. A. Lockerbie52, D. Lodhia10, M. Lormand3, P. Lu6, J. Luan23, M. Lubinski7, H. Lu¨ck4,11, A. P. Lundgren25,
1. E. Macdonald2, B. Machenschalk4,11,, M. MacInnis15, M. Mageswaran1, K. Mailand1, I. Mandel43, V. Mandic41,
0 A. Marandi6, S. Ma´rka17, Z. Ma´rka17, E. Maros1, I. W. Martin2, R. M. Martin8, J. N. Marx1, K. Mason15,
F. Matichard15, L. Matone17, R. A. Matzner44, N. Mavalvala15, R. McCarthy7, D. E. McClelland34,
2
S. C. McGuire40, G. McIntyre1, J. McIver28, D. J. A. McKechan36, G. Meadors32, M. Mehmet4,11, T. Meier4,11,
1
A. Melatos35, A. C. Melissinos53, G. Mendell7, R. A. Mercer5, S. Meshkov1, C. Messenger4,11, M. S. Meyer3,
:
v H. Miao16, J. Miller2, Y. Mino23, V. P. Mitrofanov20, G. Mitselmakher8, R. Mittleman15, O. Miyakawa47,
i B. Moe5, P. Moesta12, S. D. Mohanty18, D. Moraru7, G. Moreno7, K. Mossavi4,11, C. M. Mow-Lowry34,
X
G. Mueller8, S. Mukherjee18, A. Mullavey34, H. Mu¨ller-Ebhardt4,11, J. Munch48, D. Murphy17, P. G. Murray2,
r T. Nash1, R. Nawrodt2, J. Nelson2, G. Newton2, A. Nishizawa47, D. Nolting3, L. Nuttall36, B. O’Reilly3,
a R. O’Shaughnessy21, E. Ochsner27, J. O’Dell26, G. H. Ogin1, R. G. Oldenburg5, C. Osthelder1, C. D. Ott23,
D. J. Ottaway48, R. S. Ottens8, H. Overmier3, B. J. Owen21, A. Page10, Y. Pan27, C. Pankow8, M. A. Papa12,5,
P. Patel1, M. Pedraza1, L. Pekowsky25, S. Penn54, C. Peralta12, A. Perreca10,b, M. Phelps1, M. Pickenpack4,11,
I. M. Pinto55, M. Pitkin2, H. J. Pletsch4,11, M. V. Plissi2, J. Podkaminer54, J. Po¨ld4,11, F. Postiglione37,
V. Predoi36, L. R. Price5, M. Prijatelj4,11, M. Principe55, S. Privitera1, R. Prix4,11, L. Prokhorov20,
O. Puncken4,11, V. Quetschke18, F. J. Raab7, H. Radkins7, P. Raffai45, M. Rakhmanov18, C. R. Ramet3,
B. Rankins29, S. R. P. Mohapatra28, V. Raymond43, K. Redwine17, C. M. Reed7, T. Reed56, S. Reid2,
D. H. Reitze8, R. Riesen3, K. Riles32, P. Roberts57, N. A. Robertson1,2, C. Robinson36, E. L. Robinson12,
S. Roddy3, J. Rollins17, J. D. Romano18, J. H. Romie3, C. Ro¨ver4,11, S. Rowan2, A. Ru¨diger4,11, K. Ryan7,
S. Sakata47, M. Sakosky7, F. Salemi4,11, M. Salit43, L. Sammut35, L. Sancho de la Jordana49, V. Sandberg7,
V. Sannibale1, L. Santamara12, I. Santiago-Prieto2, G. Santostasi58, S. Saraf59, B. S. Sathyaprakash36,
S. Sato47, P. R. Saulson25, R. Savage7, R. Schilling4,11, S. Schlamminger5, R. Schnabel4,11, R. M. S. Schofield24,
B. Schulz4,11, B. F. Schutz12,36, P. Schwinberg7, J. Scott2, S. M. Scott34, A. C. Searle1, F. Seifert1,
D. Sellers3, A. S. Sengupta1,c, A. Sergeev51, D. A. Shaddock34, M. Shaltev4,11, B. Shapiro15, P. Shawhan27,
T. Shihan Weerathunga18, D. H. Shoemaker15, A. Sibley3, X. Siemens5, D. Sigg7, A. Singer1, L. Singer1,
A. M. Sintes49, G. Skelton5, B. J. J. Slagmolen34, J. Slutsky9, R. Smith10, J. R. Smith60, M. R. Smith1,
2 Abbott et al.
N. D. Smith15, K. Somiya23, B. Sorazu2, J. Soto15, F. C. Speirits2, A. J. Stein15, J. Steinlechner4,11,
S. Steinlechner4,11, S. Steplewski22, M. Stefszky34, A. Stochino1, R. Stone18, K. A. Strain2, S. Strigin20,
A. S. Stroeer30, A. L. Stuver3, T. Z. Summerscales57, M. Sung9, S. Susmithan16, P. J. Sutton36, G. P. Szokoly45,
D. Talukder22, D. B. Tanner8, S. P. Tarabrin4,11, J. R. Taylor4,11, R. Taylor1, P. Thomas7, K. A. Thorne3,
K. S. Thorne23, E. Thrane41, A. Thu¨ring4,11, K. V. Tokmakov52, C. Torres3, C. I. Torrie1,2, G. Traylor3,
M. Trias49, K. Tseng6, D. Ugolini61, K. Urbanek6, H. Vahlbruch4,11, B. Vaishnav18, M. Vallisneri23, C. Van Den
Broeck36, M. V. van der Sluys43, A. A. van Veggel2, S. Vass1, R. Vaulin5, A. Vecchio10, J. Veitch36,
P. J. Veitch48, C. Veltkamp4,11, A. E. Villar1, C. Vorvick7, S. P. Vyachanin20, S. J. Waldman15, L. Wallace1,
A. Wanner4,11, R. L. Ward1, P. Wei25, M. Weinert4,11, A. J. Weinstein1, R. Weiss15, L. Wen16,23, S. Wen3,
P. Wessels4,11, M. West25, T. Westphal4,11, K. Wette4,11, J. T. Whelan62, S. E. Whitcomb1, D. White38,
B. F. Whiting8, C. Wilkinson7, P. A. Willems1, H. R. Williams21, L. Williams8, B. Willke4,11,
L. Winkelmann4,11, W. Winkler4,11, C. C. Wipf15, A. G. Wiseman5, G. Woan2, R. Wooley3, J. Worden7,
J. Yablon43, I. Yakushin3, K. Yamamoto4,11, H. Yamamoto1, H. Yang23, D. Yeaton-Massey1, S. Yoshida63, P. Yu5,
M. Zanolin46, L. Zhang1, Z. Zhang16, C. Zhao16, N. Zotov56, M. E. Zucker15, J. Zweizig1
1LIGO-CaliforniaInstituteofTechnology,Pasadena,CA91125,USA
2UniversityofGlasgow,Glasgow,G128QQ,UnitedKingdom
3LIGO-LivingstonObservatory,Livingston,LA70754,USA
4Albert-Einstein-Institut,Max-Planck-Institutfu¨rGravitationsphysik,D-30167Hannover,Germany
5UniversityofWisconsin–Milwaukee,Milwaukee,WI53201,USA
6StanfordUniversity,Stanford,CA94305,USA
7LIGO-HanfordObservatory,Richland,WA99352,USA
8UniversityofFlorida,Gainesville,FL32611,USA
9LouisianaStateUniversity,BatonRouge,LA70803,USA
10UniversityofBirmingham,Birmingham,B152TT,UnitedKingdom
11LeibnizUniversit¨atHannover,D-30167Hannover,Germany
12Albert-Einstein-Institut,Max-Planck-Institutfu¨rGravitationsphysik,D-14476Golm,Germany
13MontanaStateUniversity,Bozeman,MT59717,USA
14CarletonCollege,Northfield,MN55057,USA
15LIGO-MassachusettsInstituteofTechnology,Cambridge,MA02139,USA
16UniversityofWesternAustralia,Crawley,WA6009,Australia
17ColumbiaUniversity,NewYork,NY10027,USA
18TheUniversityofTexasatBrownsvilleandTexasSouthmostCollege,Brownsville,TX78520,USA
19SanJoseStateUniversity,SanJose,CA95192,USA
20MoscowStateUniversity,Moscow,119992,Russia
21ThePennsylvaniaStateUniversity,UniversityPark,PA16802,USA
22WashingtonStateUniversity,Pullman,WA99164,USA
23Caltech-CaRT,Pasadena,CA91125,USA
24UniversityofOregon,Eugene,OR97403,USA
25SyracuseUniversity,Syracuse,NY13244,USA
26RutherfordAppletonLaboratory,HSIC,Chilton,Didcot,OxonOX110QXUnitedKingdom
27UniversityofMaryland,CollegePark,MD20742,USA
28UniversityofMassachusetts-Amherst,Amherst,MA01003,USA
29TheUniversityofMississippi,University,MS38677,USA
30NASA/GoddardSpaceFlightCenter,Greenbelt,MD20771,USA
31TsinghuaUniversity,Beijing100084,China
32UniversityofMichigan,AnnArbor,MI48109,USA
33CharlesSturtUniversity,WaggaWagga,NSW2678,Australia
34AustralianNationalUniversity,Canberra,0200,Australia
35TheUniversityofMelbourne,ParkvilleVIC3010,Australia
36CardiffUniversity,Cardiff,CF243AA,UnitedKingdom
37UniversityofSalerno,I-84084Fisciano(Salerno),ItalyandINFN(SezionediNapoli),Italy
38TheUniversityofSheffield,SheffieldS102TN,UnitedKingdom
39Inter-UniversityCentreforAstronomyandAstrophysics,Pune-411007,India
40SouthernUniversityandA&MCollege,BatonRouge,LA70813,USA
41UniversityofMinnesota,Minneapolis,MN55455,USA
42CaliforniaInstituteofTechnology,Pasadena,CA91125,USA
43NorthwesternUniversity,Evanston,IL60208,USA
44TheUniversityofTexasatAustin,Austin,TX78712,USA
45E¨otvo¨sLor´andUniversity,Budapest,1117Hungary
46Embry-RiddleAeronauticalUniversity,Prescott,AZ86301,USA
47NationalAstronomicalObservatoryofJapan,Tokyo181-8588,Japan
48UniversityofAdelaide,Adelaide,SA5005,Australia
49UniversitatdelesIllesBalears,E-07122PalmadeMallorca,Spain
50UniversityofSouthampton,Southampton,SO171BJ,UnitedKingdom
51InstituteofAppliedPhysics,NizhnyNovgorod,603950,Russia
52UniversityofStrathclyde,Glasgow,G11XQ,UnitedKingdom
53UniversityofRochester,Rochester,NY14627,USA
54HobartandWilliamSmithColleges,Geneva,NY14456,USA
55UniversityofSannioatBenevento,I-82100Benevento,ItalyandINFN(SezionediNapoli),Italy
56LouisianaTechUniversity,Ruston,LA71272,USA
57AndrewsUniversity,BerrienSprings,MI49104,USA
58McNeeseStateUniversity,LakeCharles,LA70609,USA
59SonomaStateUniversity,RohnertPark,CA94928,USA
60CaliforniaStateUniversityFullerton,FullertonCA92831,USA
61TrinityUniversity,SanAntonio,TX78212,USA
62RochesterInstituteofTechnology,Rochester,NY14623,USA
63SoutheasternLouisianaUniversity,Hammond,LA70402,USA
Implications for the Origin of GRB 051103 from LIGO Observations 3
a nowattheCanadianInstituteforTheoreticalAstrophysics,UniversityofToronto,Toronto,Ontario,M5S3H8,Canada
b nowatDepartmentofPhysics,UniversityofTrento,38050,Povo,Trento,Italy and
c nowattheDepartmentofPhysicsandAstrophysics,UniversityofDelhi,Delhi110007,India
M. A. Bizouard1, A. Dietz2, G. M. Guidi3ab, and M. Was1
1LAL,Universit´eParis-Sud,IN2P3/CNRS,F-91898Orsay,France
2Laboratoired’Annecy-le-VieuxdePhysiquedesParticules(LAPP),Universit´edeSavoie,CNRS/IN2P3,F-74941Annecy-Le-Vieux,
Franceand
3INFN,SezionediFirenze,I-50019SestoFiorentinoa;Universita`degliStudidiUrbino’CarloBo’,I-61029Urbinob,Italy
(Dated: January 26, 2012)
LIGO-P1000097-v12
ABSTRACT
WepresenttheresultsofaLIGOsearchforgravitationalwaves(GWs)associatedwithGRB051103,
a short-duration hard-spectrum gamma-ray burst whose electromagnetically determined sky position
is coincident with the spiral galaxy M81, which is 3.6Mpc from Earth. Possible progenitors for short-
hard GRBs include compact object mergers and soft gamma repeater (SGR) giant flares. A merger
progenitor would produce a characteristic GW signal that should be detectable at the distance of
M81, while GW emission from an SGR is not expected to be detectable at that distance. We found
no evidence of a GW signal associated with GRB 051103. Assuming weakly beamed γ-ray emission
with a jet semi-angle of 30◦ we exclude a binary neutron star merger in M81 as the progenitor with a
confidence of 98%. Neutron star-black hole mergers are excluded with >99% confidence. If the event
occurredinM81ourfindingssupportthehypothesisthatGRB051103wasduetoanSGRgiantflare,
making it the most distant extragalactic magnetar observed to date.
Subject headings: gamma-raybursts–gravitationalwaves–compactobjectmergers–softgamma-ray
repeaters
1. INTRODUCTION
GRB 051103 was a short-duration, hard-spectrum
gamma-ray burst (GRB) which occurred at 09:25:42
UTC on 3 November 2005 (Hurley et al. 2010) and was
possibly located in the nearby galaxy M81, at a distance
3.63±0.14Mpc from Earth(Golenetskii et al. 2005; Dur-
rell et al. 2010). A preliminary quadrilateral error box
obtainedbythethirdinterplanetarynetworkofsatellites
(IPN3) was consistent with a source in the M81 group
(Golenetskii et al. 2005). The refined 3-σ error ellipse,
shown with a solid black line in Figure1, has an area of
104 square arcminutes, and excludes the possibility that
theGRB’ssourcewastheinnerdiskofM81(Hurleyetal.
2010). The location of the progenitor of GRB 051103 is,
however, consistent with the outer disk of M81.
Two other galaxies are noted to lie within the original
error box: PGC028505 (distance estimated at 80Mpc,
Lipunov et al. (2005)) and PGC2719634 (distance un-
known). PGC2719634 lies on the 18% confidence con-
tour of the refined ellipse and constitutes a plausible
host galaxy. PCG028505, however, lies on the 0.03%
contour and is unlikely to be the host. Furthermore, Fig. 1.—ThecentralregionoftheM81group,showingtheorigi-
PGC028505 was observed in the R and V bands but nalerrortrapezium(reddashedline)fromtheIPNandtherefined
no evidence for brightening due to an underlying tran- 3-σerrorellipse(solidblack). Theblueboxesaretheregionsstud-
ied in the optical. Figure from Hurley et al. (2010) Copyright (c)
sient source was found (Klose et al. 2005) and it is not
2010RAS.
thought to be a plausible host of GRB 051103 (Hurley
et al. 2010; Lipunov et al. 2005). Observations of the
original quadrilateral error box in optical and radio con- references therein). With the right combination of bi-
cluded that GRB 051103 was not associated with any nary masses and spins, the neutron star matter is be-
typical supernova at z (cid:2) 0.15 (Ofek et al. 2006). None lieved to be tidally disrupted leading to the formation
of the known supernova remnants in M81 fall within the of a massive torus. Accretion of matter from this torus
refined elliptical error region. onto the final post-merger object leads to the formation
The progenitors of most short duration GRBs are ofhighlyrelativisticoutflowsalongtheaxisoftotalangu-
widely thought to be the coalescence of a neutron star- lar momentum of the system (e.g., Setiawan et al. 2004;
neutron star (NS-NS) or neutron star-black hole (NS- Shibata&Taniguchi2006;Rezzollaetal.2011). Internal
BH) binary system (see, for example, Nakar 2007 and shocksintherelativisticjetgiverisetothepromptγ-ray
4 Abbott et al.
emission observed in short, hard GRBs. The data was calibrated as described in Abadie et al.
These binary systems also produce a characteristic (2010a). The validity of the calibration was established
gravitational-wave (GW) signal in the last few seconds bycomparingrecordsofthedetectorconfigurationatthe
before coalescence that is detectable by the current gen- GRBepochtothosenearthestartofthesciencerun,and
erationofinterferometricGWdetectors,suchasthoseof estimatesofthecalibrationuncertaintyareaccountedfor
theLaserInterferometerGravitational-waveObservatory intheGWsearches. Dataqualitystudiesandtechniques
(LIGO,Abbottetal.2004,2009a), toO(10)Mpc. Thus, for vetoing problematic segments were similar to those
ifM81wasindeedthehostofabinarymergerprogenitor used during S5 (Abbott et al. 2009b). These detector
of GRB 051103, LIGO should have detected a GW sig- characterization studies have established that the data
nal associated with the event. A similar hypothesis was is of science quality and equivalent to that shortly after
tested for GRB 070201, whose error box overlapped the the official start of S5.
spiralarmsofM31(whichis770kpcfromEarth). LIGO In this paper we report on the LIGO search for GWs
was able to exclude a compact binary progenitor in M31 associated with GRB 051103, and the resulting impli-
at >99% confidence (Abbott et al. 2008a) and placed a cations for the origin of this GRB. Three independent
lower limit of 3.5Mpc on its distance at 90% confidence. analysis packages, designed for different purposes, were
Up to 15% of short GRBs might be giant flares from used. In§2wedescribethemethodandresultsofsearch-
softgammarepeaters(SGRs)inthelocaluniverse(Tan- ing for theoretically predicted gravitational waveforms
viretal.2005;Chapmanetal.2009). SGRsarebelieved emitted during compact binary mergers. In § 3, we de-
tobemagnetars;neutronstarswithextremelylargemag- scribe the results of two searches using analyses which
neticfields(B ∼1015G).However, onlyafewpercentof aredesignedtobesensitivetounmodelledshort-duration
short GRBs are thought to share the SGR-like proper- ((cid:2) 1s) bursts of GWs. The first is an analysis designed
tiesexhibitedbyGRB051103(Frederiksetal.2007). For to search for GW bursts from magnetar flares. The sec-
example, the light curve exhibits the steep rise (∼4ms) ondperformsasearchforgenericGWburstsfromGRBs
anddecayingtailobservedintheinitialpulsesofSGRgi- in the sensitive band of the LIGO instruments. Finally,
ant flares (Frederiks et al. 2007; Ofek et al. 2006; Hurley we summarise our findings in § 4.
et al. 2010). At the distance of M81 the characteristic
2. SEARCHFORGWSFROMACOMPACTBINARY
late-time weaker, oscillatory phase expected of a SGR
PROGENITOR
giant flare, which follows the rotation of the underly-
2.1. Search Method
ing neutron star, would not be detectable (Hurley et al.
2010). Second, the spectrum of GRB 051103 shows the ThemethodusedtosearchfortheGWsignalfrombi-
hard-to-soft evolution characteristic of SGR giant flares nary coalescence is identical to that reported in Abadie
(Frederiks et al. 2007). Also, if we assume the source et al. (2010b): matched filtering is used to correlate the-
was in M81, the isotropic electromagnetic energy release oretically motivated template waveforms with the data
is approximately 3.6×1046erg(Golenetskii et al. 2005), streams from the detectors.
consistent with the energy release (∼4×1046erg) of the The GW signal from binary coalescence is expected to
SGR 1806−20 giant flare(Hurley et al. 2005). We note precedethepromptγ-rayemissionbynomorethanafew
thatanumberofUV-brightregionscontainedwithinthe seconds. We therefore search for GW signals whose end
elliptical error box indicate star-forming regions in the timeliesinanon-sourcewindowof[−5,+1)saroundthe
outerdiskofM81whichmayhostmagnetars(Ofeketal. reported GRB time. The significance of candidate GW
2006;Hurleyetal.2010). Ifconfirmed,theidentification signals is estimated from the background distribution of
ofanSGRinM81wouldbethesecondandmostdistant 324 off-source trials, each 6s long (the number of which
extra-galactic SGR flare observed to date. is dictated by the quality of the data around the time of
Several searches for GWs associated with magnetar the GRB).
events have already been performed (Abbott et al. 2007, The form of the GW signal from compact binary coa-
2008b, 2009c; Abadie et al. 2011). No evidence of lescence depends on the masses (mNS,mcomp) and spins
a GW signal was found in these searches, including of the neutron star and its companion (either a neutron
the 2004 giant flare from the Galactic magnetar SGR star or a black hole), as well as the spatial location rel-
1806−20, which is a factor of ∼300 closer to Earth than ative to the detectors, the inclination angle ι between
M81(Abbottetal.2008b). AdetectableGWsignalfrom the orbital axis and the line of sight, and the polariza-
a magnetar giant flare in M81 would therefore probably tion angle specifying the orientation of the orbital axis.
require>105 moreenergyintheGWemissionoverSGR The data from each detector is filtered through a dis-
1806−20. cretebankoftemplatewaveformsdesignedsuchthatthe
At the time of the GRB, the LIGO detectors were in maximum loss of signal-to-noise ratio (SNR) due to dis-
final preparations for their fifth science run, S5, which cretizationeffectsforabinarywithnegligiblespinsis3%.
began the following day. For this reason, the data from Although the template bank used ignores spin, we later
aroundthetimeofGRB051103hasnotbeenincludedin evaluate our sensitivity to spinning systems and verify
previous searches associated with GRBs or SGRs in S5 thatsuchsystemsarestilldetectable. Itisassumedthat
data. Nonetheless, data taken by the LIGO 2km detec- at least one member of the binary is a neutron star with
torinHanford,WA(H2)andtheLIGO4kmdetectorin mass 1M(cid:3) ≤ mNS ≤ 3M(cid:3). For the companion object,
Livingston, LA (L1) is available. Motivated by interest we test masses in the range 1M(cid:3) ≤ mcomp ≤ 25M(cid:3) to
from the astronomical community and the potential for allow the possiblity of a either a neutron star-neutron
a GW detection, we have performed a search using the star or neutron star-black hole merger. We note that
established data analysis pipelines from the S5 searches. black hole masses greater than 25M(cid:3) seem likely to
“swallow” the neutron star whole, without tidally dis-
Implications for the Origin of GRB 051103 from LIGO Observations 5
rupting the neutron star and forming a sufficiently mas- pulsar(Hesselsetal.2006). OurfiducialNS-BHsystems
siveaccretiondisktopoweraGRBjet(Belczynskietal. have black hole masses drawn from Gaussian with mean
2008). 10.0M(cid:3), standard deviation 6.0M(cid:3) and truncated at
If the matched filter SNR exceeds a threshold, the [2.0,25.0]M(cid:3). To reflect the greater uncertainty arising
template masses and the time of the maximum SNR fromalackofobservedNS-BHsystems,theneutronstar
are recorded. These triggers between detectors are then mass is drawn from a Gaussian distribution with mean
testedforcoincidenceintheirtimeandmassparameters 1.4M(cid:3) andstandarddeviation0.4M(cid:3). Blackholespins
(Robinson et al. 2008). This significantly reduces the aredistributeduniformlywithin[0.0,0.98). Additionally,
number of background triggers that arise from matched population synthesis studies of NS-BH mergers appear
filtering in each detector independently. Further back- toindicatethatthetiltangle(theanglebetweentheBH
ground suppression is achieved by applying signal con- spin direction and the NS orbital axis) must be <45◦ in
sistency tests, specifically a χ2 test (Allen 2005) and the most systems to allow for tidal disruption of the NS and
r2 veto (Rodriguez 2007). The SNR and χ2 from a sin- formation of a sufficiently massive torus able to power
gledetectorarecombinedintoaneffectiveSNR(Abbott the gamma-ray burst (Belczynski et al. 2008). Recent
etal.2008c),whichisthensummedinquadratureacross numericalsimulationsofNS-BHmergerslendsupportto
detectors to form the combined effective SNR which is thisrestrictionandfindthatthetiltangleislikely<60◦
used as the ranking statistic. (Rantsiou et al. 2008; Foucart et al. 2011). We restrict
The distribution of effective SNRs can vary signifi- the tilt angle to be <60◦.
cantly across the range of masses being searched, with The outflows from the accretion jets in a GRB are di-
shorter, higher mass templates more susceptible to non- rected along the rotational axis of the final object. Rel-
stationary background noise. Consequently, we split up ativistic beaming and collimation due to the ambient
the search space by mass and re-rank triggers in each medium confines the jet to a semi-angle θjet. The obser-
mass bin by their likelihood of having arisen due to a vation of prompt γ-ray emission is, therefore, indicative
gravitational wave signal. This is defined as the effi- thattheinclinationofthetotalangularmomentumwith
ciencywithwhichwedetectplausiblegravitationalwave respect to the line of sight lies within the jet cone. Es-
signalsdividedbythefalse-alarmprobability,foragiven timates of θjet are based on jet breaks observed in X-ray
combined effective SNR. The false-alarm probability is afterglows and vary across GRBs. Indeed, many GRBs
theprobabilityofobtainingacandidatelouderthanthat do not even exhibit a jet break. However, studies of ob-
observed in the on-source trial in the same region of served jet breaks in Swift GRB X-ray afterglows find a
mass space from noise alone; it is measured using the mean (median) value of θjet =5.4◦(6.4◦), with a tail ex-
off-sourcetrials. Thedetectionefficiencyiscomputedby tending almost to 25◦ (Racusin et al. 2009). In at least
adding simulated gravitational wave signals to the data one case where no jet break is observed, the inferred
fromoff-sourcetrialsandcountingthefractionwhichare lower limit is 25◦ and could be as high as 79◦ (Grupe
recovered by the detection pipeline. et al. 2006). In order to probe the range of predicted jet
opening angles, we perform separate sets of simulations
where the inclination of the total angular momentum is
2.2. Search Results restricted to jet semi-angles of 10◦,20◦,...,60◦ and 90◦,
Thematched-filtersearchfoundnoevidenceforaGW allowinganestimateofexclusionconfidenceasafunction
signal produced by compact binary coalescence at the of jet semi-angle.
time of GRB 051103. The most significant candidate Systematic errors are treated identically to those in
eventintheon-sourceregionaroundthetimeoftheGRB Abadieetal.(2010b): amplitudecalibrationuncertainty
had a false alarm probability of 76%. That is, there and Monte-Carlo counting statistics from injections are
was a 76% chance of observing a candidate this loud or the dominant errors. Amplitude calibration uncertainty
louder in any given off-source trial due to an accidental is accounted for by multiplying exclusion distances by
coincident noise fluctuation in each detector. 1.28×(1+δ ),whereδ istheoverallfractionaluncer-
cal cal
The null-detection result allows us tocompute the fre- tainty in amplitude calibration, estimated at 25%. This
quentist confidence with which we may exclude binary issignificantlylargerthantypicalscienceruncalibration
coalescence in M81 as the progenitor for this GRB. We uncertainties (see e.g., Abadie et al. (2010a)) as fewer
used the approach of Feldman & Cousins (1998) tocom- calibration measurements were available from this pre-
pute regions in distance where GW events would, with science run time. The factor of 1.28 corresponds to a
a given confidence, have produced results inconsistent 90% pessimistic fluctuation, assuming Gaussianity. We
with our observations. The Feldman-Cousins confidence incorporate Monte-Carlo uncertainties from the compu-
regions are computed by analyzing a family of simulated tationally limited number of simulations by stretching
gravitationalwavesignals, withachoiceofpriorsforthe the Feldman-Cousins confi(cid:2)dence regions to cover a prob-
intrinsicparametersmotivatedbyastrophysicalobserva- ability interval CL+1.28 CL(1−CL)/n, where CL is
tions. Results are quoted explicitly in terms of either a the desired confidence limit and n is the number of sim-
fiducial NS-NS or NS-BH merger. ulations used in constructing the interval.
InthecaseofNS-NSmergers,massesaredrawnfroma Figure2showsexclusionconfidenceforNS-NSandNS-
Gaussian distribution with mean 1.4M(cid:3), standard devi- BHmergersasafunctionofjetsemi-angleθ ,assuming
ation0.2M(cid:3) andtruncatedat[1.0,3.0]M(cid:3). Thedimen- a distance to M81 of 3.63Mpc. If we assujmete isotropic
sionless spins, a=Jc/GM2, where J is the spin angular γ-ray (i.e., unbeamed) emission from GRB 051103 the
momentumandM isthemass,areuniformlydistributed possibility of NS-NS coalescence in M81 as its progeni-
within [0.0,0.4]. The upper bound is chosen to be com- tor is excluded with 71% confidence. Taking a fiducial
patible with the spin of the fastest observed millisecond
6 Abbott et al.
We perform two searches for a GW burst associated
1.0 with GRB 051103. As discussed previously, there is evi-
dencethatafractionofshortGRBsarecausedbynearby
e 0.9 magnetar flares, so we perform a search tailored to the
c
n
e expected GW signal arising from such a flare. Addition-
d
nfi 0.8 ally, we perform a search for a generic GW burst in the
o
c time around the GRB.
sion 0.7 TheFlarepipeline(Kalmusetal.2007;Kalmus2008)
clu targets neutron star fundamental mode (f-mode) ring-
Ex 0.6 NS-NS downs as well as unmodeled short-duration GW signals.
NS-BH IthasbeenusedpreviouslytosearchforGWsassociated
0.5 with Galactic magnetar bursts including the December
10 20 30 40 50 60 70 80 90 2004giantflarefromSGR1806−20(Abbottetal.2008b,
Jetsemi-openingangle(deg)
2009c; Abadie et al. 2011). As in the previous mag-
netar searches, we use an on-source region of [−2,+2]s
Fig. 2.— Exclusion confidences for the two classes of compact
about the GRB 051103 trigger, and an off-source region
binary coalescences considered in the matched-filter analysis as
a function of jet semi-opening angle and assuming a distance of of1000soneithersideoftheon-sourceregiontoestimate
3.63Mpc to GRB051103. The estimate is based on simulations the significance of on-source events.
where neutron star masses are Gaussian distributed with mean Flare produces a time-frequency pixel map from the
1.4M(cid:2) and standard deviation 0.2M(cid:2). Black hole masses are
also Gaussian distributed with mean 10.0M(cid:2) and standard devi- conditioned and calibrated detector data streams in the
ation 6.0M(cid:2). The reduced confidence below 30◦ is purely due to Fourier basis, groups pixels using density-based cluster-
numericalcorrectionsforlimitedsimulationsize. ing, and sums over the group to produce events. The
data from each of the two detectors is combined by in-
cluding detector noise floor measurements and antenna
12 responses to the source sky location as weighting factors
NS-NS inthedetectionstatistic. Wedividethesearchintothree
c) 10 NS-BH frequency bands: 1–3kHz where f-modes are predicted
p
M 8 DM81 to ring; and 100–200Hz and 100–1000Hz where the de-
(
n tectors are most sensitive. In the f-mode band we use a
o
usi 6 Fourier transform length of 250ms, which we find to be
xcl optimal for f-mode signals expected to decay exponen-
%E 4 tiallywithatimescaleτ inthe100–300msrange(Benhar
90 2 et al. 2004).
The X-Pipeline analysis package (Sutton et al. 2009)
0 searches for generic GW bursts in data from arbitrary
10 20 30 40 50 60 70 80 90 networks of detectors. X-Pipeline was previously used
Jetsemi-openingangle(deg)
in the search for GW bursts associated with GRBs in
LIGO science run 5 and Virgo science run 1, in 2005–
Fig. 3.— 90%-confidence exclusion distance as a function of jet
2007(Abbottetal.2010). Sincetheanalysisisnotbased
semi-angleforbinarycoalescences,givenLIGOobservationsatthe
timeofGRB051103. on a specific GW emission model, we keep the search
parameters broad to allow for a generic GW burst. In
jet semi-angle of θ = 30◦, exclusion confidence rises particular, we define our on-source region as the interval
jet [−120,+60]s around the GRB trigger; this conservative
to 98%. NS-BH mergers with isotropic emission are ex-
cludedat93%confidence,risingto>99%forθ =30◦. window is large enough to accommodate the time delay
jet betweenaGWsignalandtheonsetofthegamma-raysig-
Toaddresshowfarwecanexcludebinarycoalescences
nal in most GRB progenitor models. We use 1.5 hours
if GRB 051103 was not in M81, figure 3 shows the
of data on either side of the on-source region as the off-
distance at which we reach 90% exclusion confidence
source region for background characterization. The fre-
as a function of jet semi-angle. Assuming unbeamed
quency band of the X-Pipeline search is 64–1792Hz.
emission, NS-NS mergers are excluded with 90% con-
fidence out to a distance of 2.1Mpc, rising to 5.2Mpc X-Pipeline combines the data streams from each de-
for θ = 30◦. The corresponding distances for NS-BH tector with weighting determined by the sensitivity of
coalejsectences are 5.3Mpc and 10.7Mpc, respectively. each detector as a function of frequency and sky posi-
tion. This yields time-frequency maps of the signal en-
Theincreaseinexclusionconfidenceforsmallerjetan-
ergy in each pixel. Candidate GW events are identified
gles is due to the fact that the average amplitude of the
astheloudest1%ofpixelsinthemap. Eachisassigneda
GWsignalfromcompactbinarycoalescenceissmallerfor
significance based on its energy and time-frequency vol-
systems whose orbital plane is viewed ‘edge-on’ (where
ume, using a χ2 distribution with two degrees of free-
thedetectorreceivesthefluxfromjustoneGWpolariza-
dom. These candidates are then refined by comparing
tion)thanforsystemsviewed‘face-on’(wherethedetec-
the degree of correlation between the H2 and L1 data
tor receives the flux from both GW polarizations); small
streams, rejecting low-correlation events as background.
jet angles imply a system closer to face-on.
Surviving events are ranked by their significance, then
3. SEARCHFORAGWBURST each is assigned a false-alarm probability by comparison
to events from the off-source region.
3.1. Search Methods
Implications for the Origin of GRB 051103 from LIGO Observations 7
3.2. Search Results The sensitivity of the matched-filter search allows us
Neither the Flare magnetar search nor the X- to confidently exclude the hypothesis that the progeni-
Pipeline analysis yield evidence for a plausible tor system was a compact binary merger progenitor in
M81. Specifically, assuming an outflow jet semi-angle
gravitational-wave burst signal associated with GRB
θ = 30◦, we exclude a NS-NS merger in M81 at 98%
051103. Consequently, we place model-dependent 90% jet
confidence. NS-BHmergerswithsimilarlybeamedemis-
confidencelevelupperlimitsontheisotropicenergyemis-
sion in gravitational waves E associated with this sion are excluded at >99% confidence. Relaxing the as-
GW sumptionofbeamingsuchthatweincludesystemswhose
GRB.
The limits from the Flare analysis were obtained for orbital plane is oriented edge-on to our line-of-sight, the
twelve types of simulated GW signals: eight f-mode confidences for NS-NS and NS-BH mergers fall to 71%
and 93%, respectively. As a measure of the distance to
ringdowns with circular and linear polarizations and de-
whichwearesensitivetosuchevents,the90%-confidence
caytimes200ms; andfourband-andtime-limitedwhite
exclusion distances for NS-NS and NS-BH systems with
noiseburstswithdurationsof11msor100msandspan-
beaming are 5.2Mpc and 10.7Mpc, respectively. As-
ningthe 100–200Hz and100–1000Hz bands. Uncertain-
sumingnobeaming,thesedistancesdropto2.1Mpcand
ties from detector calibrations and Monte Carlo statis-
5.3Mpc.
tics were folded into upper limit estimates as described
Thenullresultofthesearchesforanunmodelledburst
in Abadie et al. (2011). The best (lowest) upper limit
of GWs allows us to set upper limits on the GW en-
on E was 2.0×1051erg, for 100–200Hz white noise
GW ergy emission of GRB 051103. These limits are in the
bursts lasting 100ms. The lowest f-mode upper limit
range1051–1055erg,dependingprimarilyontheassumed
was 1.6×1054erg, for circularly polarized ringdowns at
GW frequency. These limits are several ordersof magni-
1090Hz. These are the lowest frequency signals of each
tude greater than the maximum observed electromag-
morphology; limits obtained for the other ten simulated
netic emission from SGRs, ∼ 1046erg, and the high-
signals scale with the noise floor of the LIGO detectors
est predictions of the available resevoir of energy avail-
as expected and the simulations provide a check of the
able for gravitational wave emission, so we are not able
robustness of the analysis to the large uncertainty in the
to constrain the hypothesis of an SGR progenitor for
frequency of a putative GW signal (for more details on
GRB 051103.
the simulations used see Abadie et al. 2011).
We conclude then, that it is highly unlikely that the
The upper limits produced by the broad X-Pipeline
progenitorforGRB051103wasacompactbinarymerger
search are computed in a similar way, although they
in M81. If the event indeed occurred in M81, it seems
makeuseofcircularlypolarizedsine-Gaussianwaveforms
likely on the basis of LIGO observations that this was
at 150Hz and 1000Hz (for details, including handling of
indeedthemostdistantSGRgiantflareobservedtodate.
uncertainties,seeAbbottetal.2010). Wefindupperlim-
itsonE of1.2×1052ergat150Hzand6.0×1054ergat
GW
1000Hz. We can convert these results to lower limits on
the distance to GRB 051103 as a function of E , giv-
GW The authors thank A. Rowlinson and N. Tanvir for
ing4.4Mpc(EGW/0.01M(cid:3)c2)1/2at150Hzand0.20Mpc bringing GRB 051103 to our attention. The authors
(EGW/0.01M(cid:3)c2)1/2 at 1000Hz. gratefully acknowledge the support of the United States
Even near the frequency of LIGO’s best sensitivity NationalScienceFoundationfortheconstructionandop-
our energy upper limits are several orders of magni- eration of the LIGO Laboratory and the Science and
tudelargerthanthemaximumenergyavailableforemis- Technology Facilities Council of the United Kingdom,
sion by SGRs in gravitational waves ∼ 1046–1049erg the Max-Planck-Society, and the State of Niedersach-
(deFreitasPacheco1998;Ioka2001;Owen2005;Horvath sen/Germanyforsupportoftheconstructionandopera-
2005; Corsi & Owen 2011). Indeed, the energy actually tionoftheGEO600detector. Theauthorsalsogratefully
emitted as gravitational waves may be much less than acknowledge the support of the research by these agen-
this(Kashiyama&Ioka2011;Levin&vanHoven2011). ciesandbytheAustralianResearchCouncil,theInterna-
We are therefore unable to inform the hypothesis of an tional Science Linkages program of the Commonwealth
SGR progenitor for GRB 051103. of Australia, the Council of Scientific and Industrial Re-
searchofIndia, theIstitutoNazionalediFisicaNucleare
4. CONCLUSION ofItaly, theFrenchCentreNationaldelaRechercheSci-
We analyzed data from the LIGO L1 and H2 GW de- entifique,theSpanishMinisteriodeEducacio´nyCiencia,
tectors in a frequency band spanning 40Hz to 3kHz, the Conselleria d’Economia, Hisenda i Innovaci´o of the
looking for a GW signal associated with the short-hard Govern de les Illes Balears, the Royal Society, the Scot-
GRB 051103. Three data analysis pipelines were de- tish Funding Council, the Scottish Universities Physics
ployed, two of which are designed to search for unmod- Alliance, The National Aeronautics and Space Adminis-
elled, short-duration ((cid:2) 1s) burst-like GW signals and tration, the Carnegie Trust, the Leverhulme Trust, the
one which performs a matched-filter analysis using tem- DavidandLucilePackardFoundation,theResearchCor-
plates based on the GW signal expected from compact poration, andtheAlfredP.SloanFoundation. Thisdoc-
binary mergers. No evidence was found for a GW signal ument has been assigned LIGO Laboratory document
associated with this GRB. number LIGO-P10000097-v12.
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